Do you guys recognise the knots used in the video? It's none other than the Fisherman's knot.

The Fisherman's knot is a bend knot that can be almost impossible to untie. An even stronger knot than that is the double Fisherman's knot. So if you have a friend that's always pulling pranks on you, tie their shoelaces together with this knot. If you're really planning to go overboard with the prank, you may even consider the triple Fisherman's knot! :P